Provide keyboard shortcut for 'Mark file as viewed' in MR view

As a reviewer, I would like to mark a file as viewed with a keyboard shortcut. The merge request view already has some shortcuts documented (see https://docs.gitlab.com/ee/user/shortcuts.html#merge-requests), but this specific button has none.

PS: I just noticed that when I click on 'Mark as viewed' by mouse, the input box will get the focus and keep it, so any further use of other keyboard shortcuts will not work after that - you first need to click somewhere to blur the element.